Semiconductor structures and methods for manufacturing the same are provided. The semiconductor structure includes a first well region, a second well region, a third well region, and a fourth well region. The semiconductor structure includes a dielectric wall structure formed over a boundary of the first well region and the second well region and longitudinally oriented along a first direction and first channel structures, second channel structures, third channel structures, and fourth channel structures vertically suspended. In addition, the first channel structures are attached to a first sidewall surface of the dielectric wall structure, and the second channel structures are attached to a second sidewall surface of the dielectric wall structure. Furthermore, the second channel structures have a second width in the second direction, the third channel structures have a third width in the second direction, and the second width is greater than the third width.